<template>
	<view class="container">
		<!-- 轮播图 -->
		<div id="swiper">
			<u-swiper
				:list="list1"
				indicator
				indicatorMode="line"
			></u-swiper>
		</div>
		
		<!-- 菜单栏 -->
		<view class="u-menu-wrap">
			<!-- 左菜单栏 -->
			<scroll-view scroll-y scroll-with-animation class="u-tab-view menu-scroll-view" :scroll-top="scrollTop"
			 :scroll-into-view="itemId">
				<view v-for="(item,index) in tabbar" :key="index" class="u-tab-item" :class="[current == index ? 'u-tab-item-active' : '']"
				 @tap.stop="swichMenu(index)">
					<text class="u-line-1">{{item.name}}</text>
				</view>
			</scroll-view>
			<!-- 右菜单栏 -->
			<scroll-view :scroll-top="scrollRightTop" scroll-y scroll-with-animation class="right-box" @scroll="rightScroll">
				<view class="page-view">
					<view class="class-item" :id="'item' + index" v-for="(item , index) in tabbar" :key="index">
						<view class="item-title">
							<text>{{item.name}}</text>
						</view>
						<view class="item-container">
							<view class="thumb-box" v-for="(item1, index1) in item.foods" :key="index1" @click="menuRight(1)">
								<view class="item-container-left">
									<image class="item-menu-image" src="/static/images/didi.png" mode=""></image>
								</view>
								<view class="item-container-right">
									<view>滴滴打车</view>
									<text>滴滴打车GPS</text>
									<view>CPA-10-12-12%</view>
								</view>
							</view>
						</view>
					</view>
				</view>
			</scroll-view>
		</view>
	</view>
</template>

<script>
	import classifyData from '@/data/menu.js';
	export default {
		data() {
			return {
				list1: [
					'https://cdn.uviewui.com/uview/swiper/swiper1.png',
					'https://cdn.uviewui.com/uview/swiper/swiper2.png',
					'https://cdn.uviewui.com/uview/swiper/swiper3.png',
				],
				scrollTop: 0, //tab标题的滚动条位置
				oldScrollTop: 0,
				current: 0, // 预设当前项的值
				menuHeight: 0, // 左边菜单的高度
				menuItemHeight: 0, // 左边菜单item的高度
				itemId: '', // 栏目右边scroll-view用于滚动的id
				tabbar: classifyData,
				menuItemPos: [],
				arr: [],
				scrollRightTop: 0, // 右边栏目scroll-view的滚动条高度
				timer: null, // 定时器
			}
		},
		onReady() {
			this.getMenuItemTop()
		},
		onLoad() {
			uni.login({
				success: (res) => {
					uni.request({
						url:"https://a9e2-120-84-11-195.ap.ngrok.io/home/getuser",
						data: {
							code: res.code
						},
						success: (res) => {
							if(res.data.code == 200){
								uni.setStorage({
									key: 'wxopenid',
									data: res.data.status.wxopenid,
								});
								uni.setStorage({
									key: 'order',
									data: JSON.stringify(res.data.order),
								});
							}
						},
						fail: (err) => {
							console.log(err)
						}
					})
				}
			})
		},
		methods: {
			
			menuRight(value){
				console.log(value)
				uni.navigateTo({
					url: '/pages/components/details/index'
				})
			},
			// 点击左边的栏目切换
			async swichMenu(index) {
				if(this.arr.length == 0) {
					await this.getMenuItemTop();
				}
				if (index == this.current) return;
				this.scrollRightTop = this.oldScrollTop;
				this.$nextTick(function(){
					this.scrollRightTop = this.arr[index];
					this.current = index;
					this.leftMenuStatus(index);
				})
			},
			// 获取一个目标元素的高度
			getElRect(elClass, dataVal) {
				new Promise((resolve, reject) => {
					const query = uni.createSelectorQuery().in(this);
					query.select('.' + elClass).fields({
						size: true
					}, res => {
						// 如果节点尚未生成，res值为null，循环调用执行
						if (!res) {
							setTimeout(() => {
								this.getElRect(elClass);
							}, 10);
							return;
						}
						this[dataVal] = res.height;
						resolve();
					}).exec();
				})
			},
			// 观测元素相交状态
			async observer() {
				this.tabbar.map((val, index) => {
					let observer = uni.createIntersectionObserver(this);
					// 检测右边scroll-view的id为itemxx的元素与right-box的相交状态
					// 如果跟.right-box底部相交，就动态设置左边栏目的活动状态
					observer.relativeTo('.right-box', {
						top: 0
					}).observe('#item' + index, res => {
						if (res.intersectionRatio > 0) {
							let id = res.id.substring(4);
							this.leftMenuStatus(id);
						}
					})
				})
			},
			// 设置左边菜单的滚动状态
			async leftMenuStatus(index) {
				this.current = index;
				// 如果为0，意味着尚未初始化
				if (this.menuHeight == 0 || this.menuItemHeight == 0) {
					await this.getElRect('menu-scroll-view', 'menuHeight');
					await this.getElRect('u-tab-item', 'menuItemHeight');
				}
				// 将菜单活动item垂直居中
				this.scrollTop = index * this.menuItemHeight + this.menuItemHeight / 2 - this.menuHeight / 2;
			},
			// 获取右边菜单每个item到顶部的距离
			getMenuItemTop() {
				new Promise(resolve => {
					let selectorQuery = uni.createSelectorQuery();
					selectorQuery.selectAll('.class-item').boundingClientRect((rects) => {
						// 如果节点尚未生成，rects值为[](因为用selectAll，所以返回的是数组)，循环调用执行
						if(!rects.length) {
							setTimeout(() => {
								this.getMenuItemTop();
							}, 10);
							return ;
						}
						rects.forEach((rect) => {
							// 这里减去rects[0].top，是因为第一项顶部可能不是贴到导航栏(比如有个搜索框的情况)
							this.arr.push(rect.top - rects[0].top);
							resolve();
						})
					}).exec()
				})
			},
			// 右边菜单滚动
			async rightScroll(e) {
				this.oldScrollTop = e.detail.scrollTop;
				if(this.arr.length == 0) {
					await this.getMenuItemTop();
				}
				if(this.timer) return ;
				if(!this.menuHeight) {
					await this.getElRect('menu-scroll-view', 'menuHeight');
				}
				setTimeout(() => { // 节流
					this.timer = null;
					// scrollHeight为右边菜单垂直中点位置
					let scrollHeight = e.detail.scrollTop + this.menuHeight / 2;
					for (let i = 0; i < this.arr.length; i++) {
						let height1 = this.arr[i];
						let height2 = this.arr[i + 1];
						// 如果不存在height2，意味着数据循环已经到了最后一个，设置左边菜单为最后一项即可
						if (!height2 || scrollHeight >= height1 && scrollHeight < height2) {
							this.leftMenuStatus(i);
							return ;
						}
					}
				}, 10)
			}
		}
	}
</script>

<style lang="scss" scoped>
	#swiper{
		padding: 20rpx;
	}
	.container{
		height: 100vh;
		display: flex;
		flex-direction: column;
		font-size: 26rpx;
	}
		.u-menu-wrap {
			flex: 1;
			display: flex;
			overflow: hidden;
		}
	
		.u-search-inner {
			background-color: rgb(234, 234, 234);
			border-radius: 100rpx;
			display: flex;
			align-items: center;
			padding: 10rpx 16rpx;
		}
	
		.u-search-text {
			font-size: 26rpx;
			color: $u-tips-color;
			margin-left: 10rpx;
		}
	
		.u-tab-view {
			width: 270rpx;
			height: 100%;
			background: #f6f6f6;
		}
	
		.u-tab-item {
			height: 110rpx;
			background: #f6f6f6;
			box-sizing: border-box;
			display: flex;
			align-items: center;
			justify-content: center;
			font-size: 26rpx;
			color: #444;
			font-weight: 400;
			line-height: 1;
		}
	
		.u-tab-item-active {
			position: relative;
			color: #000;
			font-size: 30rpx;
			font-weight: 600;
			background: #fff;
		}
	
		.u-tab-item-active::before {
			content: "";
			position: absolute;
			border-left: 4px solid red;
			height: 32rpx;
			left: 0;
			top: 39rpx;
		}
	
		.u-tab-view {
			height: 100%;
		}
	
		.right-box {
			background-color: rgb(250, 250, 250);
		}
	
		.page-view {
			padding: 16rpx;
		}
	
		.class-item {
			margin-bottom: 30rpx;
			background-color: #fff;
			padding: 16rpx;
			border-radius: 8rpx;
		}
	
		// .class-item:last-child {
		// 	min-height: 100vh;
		// }
	
		.item-title {
			font-size: 26rpx;
			color: $u-main-color;
			font-weight: bold;
		}
	
		.item-menu-name {
			font-weight: normal;
			font-size: 24rpx;
			color: $u-main-color;
		}
	
		.item-container {
			display: flex;
			flex-wrap: wrap;
		}
	
		.thumb-box {
			display: flex;
			margin-top: 20rpx;
			font-size: 28rpx;
			width: 100%;
			.item-container-left{
				display: flex;
				justify-content: center;
				align-items: center;
			}
			
			.item-container-right view:nth-of-type(2){
				font-size: 26rpx;
				border: 2px solid #bc1714;
				color: #bc1714;
				padding: 4rpx 10rpx;
				border-radius: 8rpx;
				font-size: 20rpx;
			}
			.item-container-right text{
				display: block;
				color: #bbbbbb;
				margin: 10rpx 0;
			}
			
			.item-menu-image {
				width: 120rpx;
				height: 120rpx;
				margin-right: 20rpx;
			}
		}
	
		
</style>
